The present invention generally relates to combines that pull a grain trailer for extra storage capacity, and more particularly to a grain trailer which is integrated with the combine wherein grain trailer is both powered and steerable.
Modem grain combines, such as those used to harvest corn, wheat, soy beans, etc., and corn pickers, have significantly increased their throughput capability. These increases have resulted from improvements such as wider cutting heads and increased number of row units per machine in the case of row crops such as corn. The threshing and grain separating capacity of the machines has increased in parallel by building larger machines with higher horsepower engines.
Concomitant therewith, the number of acres in the average North American farm has increased dramatically with crop fields becoming larger and longer. Fields with a row length of one-half mile have become quite common.
The result of these simultaneous trends is that the amount of harvested crop or clean grain produced in one round or two lengths of the field has increased dramatically. The harvested grain must be carried along by the harvesting system until the end of the field is reached where it is transferred into a bulk transportation vehicle such as a truck (tractor-trailer or semi) or wagon. Combines have an onboard grain hopper in which to store the harvested grain until the end of the field has been reached. Seed corn pickers typically pull a trailer or wagon, or a truck is driven along side them to receive the grain.
Due to increased combine throughput and long fields, virtually no combine commercially available today has sufficient capacity in its on-board hopper to store the corn harvested during one round of an 80 acre field or a field which is one-half mile in length with the crop yields typically found in the U.S. corn belt. The on-board primary storage hoppers are limited in capacity by the physical size of the machine and the total weight of the combine with a full hopper which can be carried on 2 axles or 2 tracks in some cases.
Farmers and farm equipment manufacturers have addressed this problem by developing intermediate transport grain carts or trailers which are pulled by a separate tractor and operator. The grain cart/tractor combination is stationed at the opposite end of the field from the road transport (bulk storage) vehicle or along the length of the field to receive the grain from the combine when its primary hopper is full and before the combine reaches the end of the field where the road transport vehicle is located. The traditional grain cart has self-unloading capability usually in the form of an auger, conveyor, or side hydraulic dump mechanism which receives power from the tractor. The grain cart/tractor combination typically carries the grain to the end of the field and loads it into the road transport vehicle, such as a semi-truck. Examples of such grain wagons can be found in U.S. Pats. Nos. 5,013,208 and 5,340,265, and 5,409,344.
Grain cart capacities typically vary from 400 bushels to 1000 bushels. Therefore, a loaded grain cart and pulling tractor may weigh as much as 90,000 pounds. Repeated trips across the field by this large vehicle combination can produce additional soil compaction, particularly in wet conditions, which reduces future crop yields. This method of intermediate storage and movement of grain with the field incrementally adds one operator and significant capital cost to the harvesting process.
In the field of trailers or wagons that are towed by a farm tractor or over-the-road tractor-trailers (so-called "semis"), U.S. Pat. No. 2,667,028 shows a towable combine with an attached grain cart. U.S. Pat. No. 4,460,193 shows a pull type swather assembly which can be crabbed. U.S. Pat. No. 4,359,854 shows a tractor drawn combine which also can be crabbed. U.S. Pat. No. 5,412,929 shows the ability to steer a pair of rakes being towed by a tractor. U.S. Pat. No. 5,579,228 shows a servo steering control system for a non-powered trailer that includes forward and backward motion. U.S. Pat. No. 5,209,320 shows an articulated crop pesticide sprayer adapted to be pulled. U.S. Pat. No. 4,740,006 proposes to retrofit existing tractor trailers with a remote-control steering system. Finally, U.S. Pat. No. 5,329,451 proposes a steerable trailer and steering apparatus which includes a servo control.
None of these art proposals would appear to aid the farmer in extending his time in harvesting fields with consequent cost reductions. It would be advantageous if the combine itself could pull the grain trailer, however, power requirements would make it difficult for the combine to pull a full grain trailer. Then, too, the grain chute on present-day harvesters are unable to unload their grain directly behind them which is where the grain trailer would be if it were pulled by the harvester. Thus, a problem exists in this art field.